Geo log i cal Quar terly, 2012, 56 (1): 215–224
Arthrodendron borberensis sp. nov., a large pro tist (Foraminifera) from the Pagliaro For ma tion (Paleocene), North ern Apennines, It aly
Al fred UCHMAN, Mi chael A. KAMINSKI and Bruno RATTAZZI
Uchman A., Kaminski M. A. and Rattazzi B. (2011) – Arthrodendron borberensis sp. nov., a large pro tist (Foraminifera) from the Pagliaro For ma tion (Paleocene), North ern Apennines, It aly. Geol Quart., 56 (1): 215–224. Warszawa.
Arthrodendron borberensis sp. nov. is de scribed from the Pagliaro For ma tion (Paleocene) of the North ern Apennines. Spec i mens of the new spe cies are pre served on the sole of a turbiditic sand stone bed. Arthrodendron borberensis sp. nov. is char ac ter ized by its long cham - bers (some ex ceed ing 10 mm in length), its gen er ally straight course, and rare branch ing at an acute an gle. This large foraminifer lived infaunally within the sed i ment and pos si bly as epifauna af ter ex hu ma tion by ero sion, prior to the de po si tion of the host turbiditic sand - stone bed. As sem blages of smaller ag glu ti nated foraminifera (a flysch-type fauna) and trace fos sils (Nereites ichnofacies) point to a deep-sea en vi ron ment for the dis cussed pro tist.
Al fred Uchman, In sti tute of Geo log i cal Sci ences, Jagiellonian Uni ver sity, 30-063 Kraków, Po land, e-mail: al fred.uchman@.uj.edu.pl;
Michal A. Kaminski, Earth Sci ences De part ment, King Fahd Uni ver sity of Pe tro leum and Min er als, Dhahran, 31261, Saudi Ara bia, e-mail: kaminski@kfupm.edu.sa; Bruno Rattazzi, Museo Paleontologico di Crocefieschi, Via alla Chiesa 12, 16010 Crocefieschi (Genova), It aly (re ceived: Feb ru ary 2, 2012; ac cepted: March 12, 2012).
Key words: It aly, Liguria, flysch, micropalaeontology, tax on omy, Arthrodendron.
INTRODUCTION
Arthrodendron is a large, rarely re ported deep-sea pro tist, which is com posed of a chain of ag glu ti nated cham bers. Be - cause of its large size, mor phol ogy, and oc cur rence on the sole of turbidite sand stones, it es capes stan dard micro palaeonto - logical ob ser va tions and was in the past mis iden ti fied as a ma - rine plant or as a trace fos sil (Kaminski et al., 2008; Kaminski et al., 2010; Kaminski and Uchman, 2011). The tax on omy of the ge nus is still poorly known, as spec i mens re cov ered by nor - mal micropalaeontological tech niques are al ways frag men tary.
The ge nus is cur rently as cribed to the foraminiferal super - family Hormosinacea, but sim i lar i ties to Komokiacea and the xenophyophores have been also noted (Kaminski et al., 2010).
Spe cies vari a tion within the Arthrodendron group is still poorly known. The ge nus in cludes its type spe cies: A. diffusum Ulrich, 1904; A. maguricum Kaminski, Uchman and Rindsberg, 2010; A. carpathicum (Neagu, 1964) and A.
moniliformis (Neagu, 1964); A. grandis (Grzybowski, 1898) and A. subnodosiformis (Grzybowski, 1898). The va lid ity of a 19th cen tury spe cies orig i nally de scribed as a fos sil alga still needs to be eval u ated, as it is pos si ble that spe cies de scribed by
Unger (1847), Heer (1877) and by Fuchs (1894) may be se nior syn onyms of some of the foraminiferal spe cies names in cur - rent us age (e.g., Brady, 1879).
The spe cies of Arthrodendron are dis tin guished on the ba - sis of the shape of the cham bers and over all test ar chi tec ture.
Tak ing into ac count these mor pho log i cal char ac ter is tics, we herein de scribe newly dis cov ered, well-pre served spec i mens of Arthrodendron from the Pagliaro For ma tion (Paleo cene) in the North ern Apennines. The spe cies is char ac ter ized by its strongly elon gated, el lip ti cal cham bers. The main aim of this pa per is to pro vide a for mal de scrip tion of this new spe cies based on a mor pho log i cal com par i son with pre vi ously de - scribed spe cies.
GEOLOGICAL SETTING
The study area (Fig. 1) is lo cated in the North ern Apennines north of Genova, in the Monte Antola Unit, which prob a bly is an allochthonous slab within the Ligurid units. The Monte Antola For ma tion (mid dle to late Campanian) is 2000–3000 m thick and com posed mostly of thick- and very thick-bed ded
mixed fine-grained car bon ate-siliciclastic flysch (e.g., Scholle, 1971a, b; Abbate and Sagri, 1982; Argnani et al., 2004). The up per part is less cal car e ous, about 600 m thick, and is dis tin - guished as the Bruggi Mem ber or the Bruggi/Selvapiana For - ma tion (late Campanian to late Maastrichtian; Abbate and Sagri, 1967). It con tains al ter nat ing thick turbiditic marls with thin-bed ded sand stones and shales. This unit is thin ner and pinches out in the Borbera Val ley (Levi et al., 2006). The Bruggi/Selvapiana For ma tion is over lain by the Pagliaro shale (Bellinzona et al., 1971; Marroni et al., 2001; Levi et al., 2006), which is also called the Pagliaro For ma tion (Marroni et al., 2002). It roughly cor re sponds to the Cabella Mem ber of the Albirola For ma tion of Abbate and Sagri (1967) (Catanzariti et al., 2007). Cal car e ous nannoplankton dates the Pagliaro For - ma tion as early Paleocene to early late Paleocene (Zones NP1–NP5; Marroni et al., 2001) or as late Maastrichtian to ear - li est late Paleocene (Zones CC25b–NP5; Levi et al., 2006;
Catanzariti et al., 2007). It is over lain un con form ably by lower Oligocene con glom er ates of the Savignone For ma tion and lo - cally by other Oligocene sed i ments, mainly the Ranzano For - ma tion (e.g., Gelati and Gnaccolini, 1978; Gnaccolini, 1988).
The Pagliaro For ma tion is about 300–400 m thick (Abbate and Sagri, 1967). It passes grad u ally from the Bruggi/Selvapiana For ma tion (Antola For ma tion s.l.) and in the lower part con tains mixed car bon ate-siliciclastic, thin- to
thick-bed ded turbidites al ter nat ing with thick shales partly rep - re sent ing turbiditic and back ground sed i men ta tion. Mas sive grey turbiditic marls are also pres ent here. Some of the marlstones are red dish in col our. Shales con tain ing thin- to me - dium-bed ded turbiditic sand stones al ter nat ing with thick beds of grey, partly turbiditic mudstones pre vail in the mid dle to up - per part of the for ma tion. The sand stones dis play Ta-d Bouma in ter vals and are rich in plant de tri tus. In some sec tions, the sand - stone beds dis play thick en ing up ward trends in pack ages about 10 m thick. Iso lated, thick beds of sand stones and marlstones are also pres ent. The en tire for ma tion is gently de formed tec - toni cally, with faults, in ter nal de tach ments, es pe cially in the up per part of the for ma tion. In some ar eas beds are over turned.
Tec tonic de for ma tions of the Antola Formation were char ac ter - ized by Marroni et al. (2002) and Levi et al. (2006). Trace fos - sils of the Pagliaro For ma tion are typ i cal of the deep-sea Nereites ichnofacies (Uchman, 2007).
The stud ied sec tion (Fig. 2) oc curs in the lower part of the Pagliaro For ma tion in the Borbera Val ley near Celio (Fig. 1), in a bank of an un named stream, which is a left trib u tary of the Borbera River. There is an iso lated out crop (GPS co-or di nates:
N 44°40.700’; E 009°05.042’; ±6 m), in which al ter nat ing sand stone and shale beds are ex posed. Arthrodendron oc curs only on the lower sur face of a sin gle, rip ple lam i nated, very fine-grained, cal car e ous, muscovitic sand stone bed (Fig. 2),
Fig. 1. Lo ca tion of the study re gion (A), area (B) and sec tion (C) of the Pagliaro For ma tion (Paleocene), Celio, North ern Apennines
that is 15–17 mm thick. A sec ond, iso lated find (spec i men 6808) co mes from a lo cal ity (Celio vil lage; an es carp ment of an aban doned for est road; GPS co-or di nates: N 44°40.662’;
E 009°04.695’) lo cated ~400 m from the main lo cal ity at a stratigraphically higher po si tion within the Pagliaro For ma tion.
SYSTEMATIC TAXONOMY
Class Foraminiferea d’Orbigny, 1826 Sub class Textulariia Mikhalevich, 1980
Or der Lituolida Lankester, 1885 Suborder Hormosinina Mikhalevich, 1980 Superfamily Hormosinacea Haeckel, 1894 Fam ily Aschemocellidae Vialov, 1966
Ge nus Arthrodendron Ulrich, 1904
D i a g n o s i s. – Branched chains of large cham bers with an im per fo rate ag glu ti nated wall that lacks biogenic bar ite crys - tals (Kaminski et al., 2008).
R e m a r k s. – Arthrodendron (= Aschemocella Vialov, 1966) dif fers from other hormosinaceans in its large di men - sions and in hav ing a branch ing septate test. The test con sists of many cham bers in a me an der ing se ries that may branch from a cen tral area. These chains of cham bers may branch fur ther. The spe cies of Arthrodendron are dis tin guished by their pre dom i - nant cham ber shape and mode of branch ing. The ge nus dif fers from Aschemonella (type spe cies A. scabra Brady, 1879) in pos sess ing well-de vel oped cham bers and in lack ing intra - cellular bar ite crys tals. Gooday and Nott (1982) found that Aschemonella ramuliformis Brady pos sesses cy to plas mic strands (termed granellare) con tain ing intracellular bar ite, and trans ferred the ge nus to the xenophyophores. This as sign ment has re cently been con firmed by Gooday et al. (2011) based on a com par i son of small sub-unit rDNA se quences.
Arthrodendron borberensis sp. nov.
(Figs. 3–6)
D e r i v a t i o n o f n a m e. – From the Borbera Val ley near Celio, It aly.
T y p e s a n d m a t e r i a l. – In the Geo log i cal Mu - seum of the Jagiellonian Uni ver sity, KrakÙw. The holotype is on slab INGUJ175P24 as in di cate in Fig ure 3A; all other spec i - mens on the slab are paratypes. Slab INGUJ175P25 con tains paratypes (Fig. 3B), slabs INGUJ175P27, 28, two pieces for SEM anal y sis (INGUJ175P29a, b), one thin sec tion (INGUJ175P30). In the Museo Crocefieschi near Genova: 15 slabs (cat a logue num bers 6800, 6808, 7003, 7154, 7164–7167, 7192–7198); slabs 7003 and 7164 con tain paratypes.
D i a g n o s i s. – Arthrodendron with strongly elon gated, mostly ovoid cham bers, of which at least some ex ceed 10 mm in length, with sparse low-an gle, di chot o mous branch ing and lin ear, straight, or gently curved chains of cham bers.
D e s c r i p t i o n. – Test free, con sist ing of a chain-like se ries of cham bers. The course of cham ber chains is lin ear, straight or slightly curved, or slightly wind ing. The lon gest spec i men at tains a to tal length of 22 cm. Most of the chains are ori ented subparallel to one an other on the bed ding plane (Fig. 4A), but with out any re la tion ship to cur rent struc tures.
The chains can over lap one an other (Fig. 3B, F). The cham ber that is over lapped is de formed by the over lap ping one (Fig. 3F).
The proloculus was ob served in only one spec i men (Fig. 3B); it con sists of a sin gle round cham ber, and is im me di ately fol - lowed by an ovoid or elon gated sec ond cham ber. Suc ces sive cham bers are long, rang ing from 1.8 to 16.3 mm (m = 7.3,
Arthrodendron borberensis sp. nov., a large protist (Foraminifera) from the Pagliaro Formation (Paleocene), Northern Apennines, Italy 217
Fig. 2. The stud ied sec tion of the Pagliaro For ma tion (Paleocene), Celio, North ern Apennines, with in di ca tion of the bed with Arthrodendron borberensis, trace fos sil oc cur rences and lo ca tion of sam ples Cl1 and Cl2 col lected for smaller foraminifers
Grain size: m – mud, s – silt, vf – very fine sand, f – fine sand, m – me dium sand, c – coarse sand
Fig. 3. Type spec i mens of Arthrodendron borberensis sp. nov. on the lower sur face of a turbiditic sand stone bed, Pagliaro For ma tion (Paleocene), Celio, North ern Apennines
A – holotype and paratypes; the quad ran gle shows the branch ing area il lus trated in Fig ure 3D (INGUJP175P24); B – paratypes; one of the spec i mens shows proloculus (pr), de tail in quad ran gle shown in Fig ure 3F (INGUJP175P25); C – other paratypes in the slab 7154; D – de tail of A show ing the a branch ing cham ber; E – spec i men INGUJP175P27; one cham ber de formed by a trace fos sil (tf); F – de tail of B show ing the cross ing (cr) of two chains of cham bers
Arthrodendron borberensis sp. nov., a large protist (Foraminifera) from the Pagliaro Formation (Paleocene), Northern Apennines, Italy 219
Fig. 4. Other spec i mens of Arthrodendron borberensis sp. nov.
from the Pagliaro For ma tion (Paleocene), Celio, North ern Apennines
A – slab 7164 with other paratypes show ing subparallel ori en ta tion, a de tail in quad ran gle shown in Fig ure 4C; B — meshes of the trace fos sil Paleodictyon (Pa) cov ered by a cham ber of A. borberensis (slab 7194); C – de tail of A show ing a branched cham ber; D – slab 7192 show ing a branched chain at the top and curved chain in the mid dle; E – pol ished slab of shale just be low the A. borberensis bear ing bed show ing ar tic u lated and disarticulated chains (Ab); F – slab 7003 with other paratypes show ing typ i cal chains of cham bers
n = 96). Usu ally, ev ery spec i men con tains cham bers lon ger than 10 mm. Cham bers vary in width be tween 1.1 and 3.2 mm (m = 1.9, n = 96). In out line, cham bers are gen er ally tu bu lar, ovoid or slightly pyriform in shape. Pyriform cham bers taper in the di rec tion of growth. Cham bers are con stricted at the septa.
Suc ces sive cham bers have only a small amount of over lap with the pre vi ous cham ber. Flat tened edges of the cham bers form a raised rim in re spect to the bed ding sur face ow ing to com pac - tion of the host bed. The sur face of the cham bers is un du lat ing or wrin kled, flat, lo cally swol len, but com monly de pressed along the ax ial zone. Some of the cham bers are plas tic ally de - formed by trace fos sils (Fig. 3E). Branch ing is very sparse,
start ing from an oc ca sional V- or Y-shaped cham ber (Figs. 3B, D and 4A, C), with branches di verg ing at an an gle of be tween 20 and 34°, mostly about 25°.
The fi nal cham ber ta pers to ward the ap er ture. Ap er ture is sin gle and ter mi nal in po si tion, with a pro duced neck. The fi nal cham ber may be kummerform: shorter, and hence more rounded than pre vi ous cham bers.
Ac cord ing to thin sec tion (Fig. 5) and SEM (Fig. 6) anal y - ses, the test wall of A. borberensis is thin (50–100 mm) and com prises three lay ers (Figs. 5B, C and 6C, D, G) that are dis - tin guished by dif fer ences in col our, grain size and com po si tion.
The fine-grained outer layer con tains mostly sil ica, which is most likely a post-depositional fea ture. The mid dle layer (25–80 mm thick) con sists of silt-sized min eral grains com - posed mainly of quartz with some feld spar. In places, this mid - dle ag glu ti nated layer is it self sub di vided by an in ter nal dark layer (Fig. 5C), which might cor re spond to the orig i nal pri mary or ganic mem brane. In this case, the in ner part of the mid dle layer is thin ner (10–15 mm thick) than the outer one (~35 mm thick). In places on the up per side of the cham ber, the dark in - ner layer and cham ber fill pro trude into the host sed i ment (Fig. 5C). The in ner layer is com posed of sil ica and clay min er - als and is welded with the fill in some cham bers (Fig. 5), while in other cham bers the fill is sim i lar to the host rock. The septa con sti tute thin tun nels sur rounded by ag glu ti nated grains like those in the mid dle layer (Fig. 5A, B).
DISCUSSION
TAXONOMIC PROBLEMS
The holotype spec i men (Fig. 3A) is in com plete (the proloculus is miss ing), but the spec i men was se lected be cause of its typ i cal cham ber shape and low-an gle branch ing that in volves a Y-shaped cham ber. In the holotype the suc ces sive branches then run par al lel to one other, but this is not al ways the case.
Arthrodendron borberensis sp. nov. is sim i lar to A. diffusum Ulrich, 1904 and A. carpathicum (Neagu, 1964) be cause of the gen er ally ovate shape of cham bers. How ever, anal y ses of cham - ber size (Fig. 7), an gle of branch ing, and course of cham ber chains show sig nif i cant dif fer ences be tween these spe cies.
The length of cham bers of A. carpathicum never ex ceeds 10 mm (1.6–8.6 mm; m = 4.6, n = 111). Its cham ber width is broader, rang ing from 1.2 to 4.6 mm (m = 2.3, n = 111). The an - gle of branches in A. carpathicum is more vari able, in clud ing cases of branch ing at right an gles, and the course of the cham ber chain is com monly wind ing (see Neagu, 1964). Cham bers of A.
diffusum (see Kaminski et al., 2008) are even shorter (0.9–4.4 mm; m = 2.9, n = 55) and nar rower (0.6–3.4 mm; m = 1.7, n = 55), and sim i larly to A. carpathicum, are smaller and the an gle of the branches is more vari able. The course of the cham - ber chain is slightly wind ing. There fore, the long cham bers (with some over 10 mm long), gen er ally straight course, and low an gle of rare branch ing are con sid ered to be the main di ag nos tic fea - tures of A. borberensis. Only the proloculus is round in out line and if found in iso la tion could be con fused with the spe cies
Fig. 5. Arthrodendron borberensis sp. nov. in ver ti cal cross-sec tion along cham bers; thin sec tion INGUJ175P30, Pagliaro For ma tion
(Paleocene), Celio, North ern Apennines
A – gen eral view of two ad ja cent cham bers with the sep tum area; B – de - tails of the sep tum area: mid dle (md) and outer (ot) layer of the wall, in ner layer of the wall and in fill ing of the cham bers (in) and sep tum tun nel (sp);
C – frag ment of cham ber show ing the in ner layer and fill ing of the cham - ber, and the mid dle layer of the wall; the lat ter, in the up per part of the test, is sub di vided into two lay ers (md 1 and md 2) sep a rated by a thin fine-grained layer; pro tru sions (pr) run up from the cham ber
Arthrodendron borberensis sp. nov., a large protist (Foraminifera) from the Pagliaro Formation (Paleocene), Northern Apennines, Italy 221
Fig. 6. SEM im ages of Arthrodendron borberensis
A – gen eral view of two in com plete cham bers and the con nect ing sep tum; B – cross-sec tion of the up per part of the test em bed ded in the sed i ment; C – cham ber with oblique cross-sec tion in the left; D – de tail of C, lay ers of the wall: ot – outer layer, md – mid dle layer, in – in ner layer, mdu – sur face of the mid dle layer (up per part of the test); E – de tail of D show ing the outer layer of the wall, which is built of sil ica; F – de tail of C, sur face of the in ner layer of the wall, which is built mostly of quartz and feld spar grains; G – de tail of D show ing the outer, mid dle and in ner lay ers if the wall; grains of quartz (Qtz) and plagioclase (Pl) in the mid dle layer de ter mined by the EDS anal y sis; H – de tail of D and party H show ing the in ner wall, which is built of sil ica and clay min er als; B – INGUJ17P29b; oth ers INGUJ17P29a
Arthrodendron grandis (Grzybowski, 1898). The straight course of A. borberensis, with out any ev i dence of re la tion to cur rent struc tures, seems to be a spe cies char ac ter is tic fea ture.
Kaminski et al. (2008) re garded the Carpathian spe cies A.
carpathicus (orig i nally Aschemonella carpathica Neagu, 1964) as a ju nior syn onym of A. diffusum Ulrich, 1904. Mea - sure ments of cham ber di men sions be tween the two spe cies show con sid er able over lap, but the gen er ally smaller cham ber length (Fig. 7) in the lat ter and its less wind ing course, can be con sid ered as fea tures al low ing their sep a ra tion.
A sep a rate prob lem is the com par i son of these fos sil taxa to re cent taxa, for ex am ple with the xenophyophore Occultammina profunda Tendal, Swinbanks and Shirayama, 1982. The ge nus Occultammina was orig i nally de scribed from a box core col lected at 8.260 m depth in the Ogasawara Trench off the Bonin Is lands in the Pa cific. Its test may be tu bu lar, un - branched, or bi fur cat ing and anastomosing at a low an gle, form ing a po lyg o nal net work. It has a lay ered test wall, and the cy to plasm con tains branched and anastomosing strings of dark stercomare. The or gan ism is infaunal, found as deep as 6 cm (but mostly be tween 2 and 3 cm) be low the sed i ment sur face (Tendal et al., 1982). Aside from the fact that Occultammina has an un di vided tu bu lar test, the over all sim i lar i ties with Arthrodendron borberensis sp. nov. in terms of both mor phol - ogy and hab i tat are strik ing. Our spec i mens of A. borberensis are infilled with a dark sub stance, which could have been de - rived from orig i nal masses of stercomata, but this in ter pre ta tion is spec u la tive and can not be con firmed in fos sil ma te rial. Com - par i sons with spe cies of Aschemonella pre served in the col lec - tions of the HMS Chal lenger Ex pe di tion at the NHM in Lon - don are more dis tant ones. The ge nus Aschemonella Brady, 1879 has a branch ing test and con sists of tu bu lar pseudochambers con nected by short sto lons, with rare short
side branches. The sev eral spe cies of Aschemonella are dif fer - en ti ated on the ba sis of the shape of the pseudochambers.
Gooday and Nott (1982) found that Aschemonella ramuliformis Brady is a xenophyophore based on its in ter nal or ga ni za tion that in cludes anastomosing stercomare strings, and granellare strands with intracellular bar ite crys tals. The syntypes pre served in the HMS Chal lenger Col lec tion are from Sta tion 244 (2900 fath oms depth in the North Pa cific) and are pre served in Slides BMHN-ZF 1111, 1112 and 1113. The syntypes dis play a wide range of cham ber form, from tu bu lar to gently curved, Y-shaped, or tu bu lar with mul ti ple side branches. The cham ber form is mostly tu bu lar and frag ments pre served in the slides are as long as 11.5 mm, but the col lec - tion mainly con sists of bro ken frag ments. The pseudochambers of Aschemonella ramuliformis are more ir reg u lar than those of our new spe cies and pos sess con stric tions and swell ings, ir reg - u larly spaced lat eral pro tu ber ances, or side branches that may di verge at right an gles. Brady cut some spec i mens open, re veal - ing a dark in ner or ganic lin ing, The test wall is thin, com posed of min eral grains sev eral grains thick, but is not vis i bly lay ered.
Aschemonella ramuliformis clearly dif fers from our new spe - cies based on its more ir reg u lar cham ber shape, the fact that it pos sesses pseudochambers in stead of true over lap ping cham - bers, and in its thin, unlayered wall. Ad di tion ally, the mod ern spe cies A. ramuliformis is known to have an erect epifaunal hab i tat, grow ing in di vid u ally or in bush-like clus ters on the sea floor (Gooday et al., 2011).
MORPHOLOGY, BEHAVIOUR AND ENVIRONMENT
Arthrodendron borberensis has a dis tinctly lay ered wall.
We spec u late that ag glu ti nated grains were at tached to both
Fig. 7. Chart show ing width ver sus length of cham bers in Arthrodendron diffusum Ulrich, 1904, A. carpathicum (Neagu, 1964) and A. borberensis sp. nov.
sides of a pri mary or ganic ma trix. On the in ner sur face of the test wall, there is an in ner finely grained, dark layer that is com - posed of sil ica and clay min er als, which may cor re spond to the orig i nal in ner or ganic lin ing. The sil ica was most likely de pos - ited on the in ner or ganic lin ing. Pro tru sions of the cham ber in - ner wall and fill that ex tend to the host rock (Fig. 5C) may be pri mary mor pho log i cal fea tures or sec ond ary ones caused by com pac tion of the test.
Arthrodendron borberensis lived within the mud as shal - low infauna, or on the muddy sur face of the sea floor. The infaunal mode of life is proven by the trace fos sil Paleodictyon pre served on the same bed ding plane, which has a hex ag o nal net that runs di rectly above one of the cham bers (Fig. 4B).
Paleodictyon is a three-di men sional bur row sys tem com posed of a hor i zon tal hex ag o nal net work con nected to the sea floor sur face by ver ti cal shafts. Pres er va tion of the hex ag o nal net re - quires an ero sive event that ex humes the net (Seilacher, 1977).
More over, ar tic u lated and disarticulated cham bers of Arthrodendron are pres ent in the mud layer be neath the host ing sand stone bed (Fig. 4E). It is pos si ble that Arthrodendron also lived on the sed i ment sur face af ter ex hu ma tion. It was killed by a weak turbiditic cur rent that de pos ited the host sand stone bed.
The test was plas tic, as shown by the de for ma tion by trace fos - sils (Fig. 3E), over lap ping, and com pac tion of the cham bers.
The foraminiferal as sem blage re cov ered from washed res i - dues of sam ple Cl1 (Fig. 2) col lected in the im me di ate prox im - ity of the Arthrodendron bed con sists en tirely of ag glu ti nated forms. The foraminiferal as sem blage is com pletely dom i nated by tu bu lar foraminifera (mostly Rhizammina with rare Psammosiphonella) and bro ken frag ments of Arthrodendron.
Nontubular forms make up less than 10% of the as sem blage, and in clude sin gle spec i mens of Psammosphaera sp., Ammodiscus peruvianus Berry, and Paratrochammina sp.
More over, Bathysiphon sp. is pres ent in the beds above the Arthrodendron-bear ing bed (Fig. 2). Con cen tra tion of tu bu lar spec i mens is a fea ture that is typ i cal of turbiditic de pos its (Kaminski et al., 1988).
The trace fos sil as sem blage from the Arthrodendron-bear - ing bed and a few un der ly ing beds (Fig. 2) in cludes Paleodictyon isp., ?Thalassinoides isp., Helminthopsis isp.,
“Arthrophycus” strictus (Książkiewicz), Ophiomorpha annulata (Książkiewicz), Scolicia isp., Halopoa isp., Nereites irregularis (Schafhäutl), and Planolites isp. This as sem blage is typ i cal of the deep-sea Paleodictyon subichnofacies of the Nereites ichnofacies (Seilacher, 1974; Uchman and Wetzel, 2011), sim i lar to the other trace fos sil as sem blages of the Pagliaro For ma tion (Uchman, 2007). Thus, the micropalaeono - logical and ichnological data point to a deep-sea turbiditic en vi - ron ment, but above the cal cium com pen sa tion depth (CCD) as sug gested by the cal car e ous char ac ter of the shales.
Ac knowl edge ments. AU was sup ported by the Fondazione Luigi, Cesare e Liliana Bertora and the Jagiellonian Uni ver sity (DS funds). Anal y ses by Scan ning Elec tron Mi cro scope equipped with EDS spec trom e ter Hitachi 4700 were made at the Jagiellonian Uni ver sity. We thank G. Miller for en abling ac cess to the Brady Col lec tion at the Nat - u ral His tory Mu seum, Lon don. A. K. Rindsberg (Living stone, Al a bama), C. Cetean (Llandudno, N. Wales) and J. Soták (Banská Bystrica) kindly re viewed the manu script.
REFERENCES
ABBATE E. and SAGRI M. (1967) – Suddivisioni litostratigrafiche nei calcari ad elmintoidi auctt. della Placca dell’Ebro-Antola e correlazioni con terreni simili affioranti tra Voghera e Castelnovo ne’
Monti (Appennino Settentrionale). Mem. Soc. Geol. Ital., 6: 23–65.
ABBATE E. and SAGRI M. (1982) – Le unit´ torbiditiche cretacee dell’Appennino settentrionale ed i margini continentali della Tetide.
Mem. Soc. Geol. Ital., 34: 115–126.
ARGNANI A., FONTANA D., STEFANI C. and ZUFFA G. G. (2004) – Late Cre ta ceous car bon ate turbidites of the North ern Apennines:
shak ing Adria at the on set of Al pine col li sion. J. Geol., 112: 251–259.
BELLINZONA G., BONI A., BRAGA G. and MARCHETTI G. (1971) – Note Il lus tra tive della Carta Geologica d’Italia alla Scala 1:100 000, Foglio 71, Voghera. Serv. Geol. Ital., Roma.
BRADY H. B. (1879) – Notes on some of the Reticularian Rhizopoda of the “Chal lenger” Ex pe di tion. Part I. On new or lit tle known arenaceous types. Quart. J. Microscop. Sc., New Ser., 19: 20–63.
CATANZARITI R., ELLERO A., LEVI N., OTTRIA G. and PANDOLFI L. (2007) – Nannofossil biostratigraphy of the Antola Unit suc ces sion (North ern Apennines, It aly): new age con straints for the Up per Cre ta - ceous Helminthoid Flysch. Cre ta ceous Res., 28: 841–860.
FUCHS T. (1894) – Über eine fossile Halimeda aus dem eocänen Sandstein von Greifenstein. Sitz. Akad. Wiss., Math.-Natur. Kl., 103:
200–204.
GELATI R. and GNACCOLINI M. (1978) – I conglomerati della Val Borbera, al margine orientale del bacino Terziario Ligure-Piemontese.
Riv. Paleont. Strat. Ital., 84: 701–728.
GNACCOLINI M. (1988) – Osservazioni sui conglomerati oligocenici affiorenti nell’area compresa tra Roccaforte Ligure e Gordona (Alessandria). Riv. Paleont. Strat. Ital., 93: 521–532.
GOODAY A. J. and NOTT J. A. (1982) – Intracellular bar ite crys tals in two new xenophyophores, Aschemonella ramuliformis and Galatheammina sp. (Pro to zoa: Rhizopoda) with com ments on the tax - on omy of A. ramuliformis. J. Mar. Biol. Ass. UK, 62: 595–605.
GOODAY A. J., ARANDA da SILVA A. and PAWLOWSKI J. (2011) – Xenophyophores (Rhizaria, Foraminifera) from the Nazaré Can yon (Por tu guese mar gin, NE At lan tic). Deep Sea Res. II, 58: 2401–2419.
GRZYBOWSKI J. (1898) – Otwornice pokładów naftonoínych okolicy Krosna. Rozpr. Wydz. Mat.-Przyr., Akad. Um. Krak., Ser. 2, 33:
257–305.
HEER O. (1877) – Flora Fossilis Helvetiae. Vorweltliche Flora der Schweiz. J. Wurster and Comp., Zürich.
KAMINSKI M. A. and UCHMAN A. (2011) – A large branched Arthrodendron spe cies (Foraminifera) from the Ropianka Beds (Senonian-Paleocene) of the Pol ish Carpathians. Grzybowski Found.
Spec. Publ., 16: 111–114.
KAMINSKI M. A., GRADSTEIN F. M., BERGGREN W. A., GEROCH S.
and BECKMANN J.-P. (1988) – Flysch-type ag glu ti nated Arthrodendron borberensis sp. nov., a large protist (Foraminifera) from the Pagliaro Formation (Paleocene), Northern Apennines, Italy 223
foraminiferal as sem blages from Trin i dad: tax on omy, stra tig ra phy and paleobathymetry. Abh. Geol. Bundesanst., Wien, 41: 155–227.
KAMINSKI M. A., UCHMAN A., NEAGU T. and CETEAN C. G. (2008) – A larger ag glu ti nated foraminifer orig i nally de scribed as a ma rine plant: the case of Arthrodendron Ulrich, 1904 (Foraminifera), its syn - onyms and hom onyms. J. Micropaleont., 27: 103–110.
KAMINSKI M. A., UCHMAN A. and RINDSBERG A. K. (2010) – Arthrodendron maguricum n. sp., a new larger ag glu ti nated foraminifer from the Eocene Magura Flysch of the Pol ish Carpathians.
J. Paleont., 84: 1015–1021.
LEVI N., ELLERO A., OTTRIA G. and PANDOLFI L. (2006) – Polyorogenic de for ma tion his tory rec og nized at very shal low struc - tural lev els: the case of the Antola Unit (North ern Apennines, It aly). J.
Struct. Geol., 28: 1694–1709.
MARRONI M., MOLLIA G., OTTRIA G. and PANDOLFI L. (2001) – Tectono-sed i men tary evo lu tion of the Ex ter nal Liguride units (North - ern Apennines, It aly): in sights in the pre-collisional his tory of a fos sil ocean-con ti nent tran si tion zone. Geodin. Acta, 14: 307–320.
MARRONI M., FERONI A. C., BIASE D. di, OTTRIA G., PANDOLFI L.
and TAINI A. (2002) – Polyphase fold ing at up per struc tural lev els in the Borbera Val ley (north ern Apennines, It aly): im pli ca tions for the tec tonic evo lu tion of the link age area be tween Alps and Apennines. C.
R. Geosc., 334: 565–572.
NEAGU T. (1964) – Large size ag glu ti nated foraminifera from the Campanian of Ru ma nian Carpathians. Rocz. Pol. Tow. Geol., 34:
579–588.
SCHOLLE P. A. (1971a) – Sedimentology of fine-grained deep-wa ter car - bon ate turbidites, Monte Antola Flysch (Up per Cre ta ceous), north ern Apennines, It aly. Bull. Geol. Soc. Am., 82: 629–658.
SCHOLLE P. A. (1971b) – Diagenesis of deep-wa ter car bon ate turbidites, up per Cre ta ceous Monte Antola flysch, north ern Apennines, It aly. J.
Sed. Petrol., 41: 233–250.
SEILACHER A. (1974) – Flysch trace fos sils: evo lu tion of be hav ioural di - ver sity in the deep-sea. Neues Jahrb. Geol Paläont., Mh., (1974):
223–245.
SEILACHER A. (1977) – Pat tern anal y sis of Paleodictyon and re lated trace fos sils. Geol. J., Spec. Is sue, 9: 289–334.
TENDAL O. S., SWINBANKS D. D. and SHIRAYAMA Y. (1982) – A new infaunal xenophyophore (Xenophyophorea, Pro to zoa) with notes on its ecol ogy and Pos si ble trace fos sil an a logues. Ocean. Acta, 5:
325–329.
UCHMAN A. (2007) – Trace fos sils of the Pagliaro For ma tion (Paleocene) in the North Apennines, It aly. Beringeria, 37: 217–237.
UCHMAN A. and WETZEL A. (2011) – Deep-sea ichnology: the re la tion - ships be tween depositional en vi ron ment and endobenthic or gan isms.
De velop. Sed., 63: 517–556.
UNGER F. (1847) – Chloris Protogaea. Beiträge zur Flora der Vorwelt.
Wil helm Engelmann, Leip zig.
